Network-Layer DDoS Attack Trends for Q1 2020

As we wrapped up the first quarter of 2020, we set out to understand if and how DDoS attack trends have shifted during this unprecedented time of global shelter in place. Since then, traffic levels have increased by over 50% in many countries, but have DDoS attacks increased as well?

Traffic increases are often observed during holiday seasons. During holidays, people may spend more time online; whether shopping, ordering food, playing online games or a myriad of other online activities. This higher usage translates into higher revenue per minute for the companies that provide those various online services.

Downtime or service degradation during these peak times could result in user churn and loss of significant revenue in a very short time. ITIC estimates that the average cost of an outage is $5,600 per minute, which extrapolates to well over $300K per hour. It is therefore no surprise that attackers capitalize on the opportunity by launching a higher number of DDoS attacks during the holiday seasons.

The current pandemic has a similar cause and effect. People are forced to stay home. They have become more reliant on online services to accomplish their daily tasks which has generated a surge in the Internet traffic and DDoS attacks.

The Rise of Smaller, Shorter Attacks

Most of the attacks that we observed in Q1 2020 were relatively small, as measured by their bit rates. As shown in the figure below, in Q1 2020, 92% of the attacks were under 10 Gbps, compared to 84% in Q4 2019.

Diving deeper, an interesting shift can be observed in the distribution of attacks below 10 Gbps in Q1, as compared to the previous quarter. In Q4, 47% of network-layer DDoS attacks peaked below 500 Mbps, whereas in Q1 they increased to 64%.

From a packet rate perspective, the majority of the attacks peaked below 1 million packets per second (pps). This rate, along with their bit rate, indicates that attackers are no longer focusing their efforts and resources to generate high-rate floods -- bits or packets per second.

However, it's not only the packet and bit rates that are decreasing, but also the attack durations. The figure below illustrates that 79% of DDoS attacks in Q1 lasted between 30 to 60 minutes, compared to 60% in Q4, which represents a 19% increase.

These three trends could be explained by the following:

Launching DDoS attacks is cheap and you don’t need much technical background. DDoS-as-a-service tools have provided a possible avenue for bad actors with little to no technical expertise to launch DDoS attacks quickly, easily, in a cost-effective manner and with limited bandwidth. According to Kaspersky, DDoS attack services can cost as little as $5 for a 300-second attack (5 minutes). Additionally, amateur attackers can also easily leverage free tools to generate floods of packets. As we’ll see in the next section, 13.5% of all DDoS attacks in Q1 were generated using variations of the publicly available Mirai code.

While an attack under 10 Gbps might seem small, it can still be enough to affect underprotected Internet properties. Smaller and quicker attacks might prove to deliver a high ROI for attackers to extort a ransom from companies in lieu of not disrupting the availability of the Internet property.

Larger Attacks Still Persist, Albeit in Smaller Numbers

While the majority of the attacks were under 10 Gbps, larger attacks are still prevalent. The below graph shows a trend in the largest bit-rate of network-layer DDoS attacks that Cloudflare has observed and mitigated in Q4 2019 and Q1 2020. The largest attack for the quarter was observed during March and peaked just above 550 Gbps.

If At First You Don’t Succeed, Try, Try Again

A persistent attacker is one that does not give up when their attacks fail; they try and try again. They launch multiple attacks on their target, often utilizing multiple attack vectors. In the Q4 2019 holiday season, attackers persisted and launched as many as 523 DDoS attacks in one day against a single Cloudflare IP. Each Cloudflare IP under attack was targeted by as many as 4.6 DDoS attacks every day on average.

During Q1, as the world entered COVID-19 lockdown, we observed a significant increase in the number of attacks compared to the monthly average. The last time we saw such an increase was in the Q4 2019 holiday season. However, an interesting difference is that attackers seem less persistent now than during the holidays. In Q1 2020, the average persistence rate dropped as low as 2.2 attacks per Cloudflare IP address per day, with a maximum of 311 attacks on a single IP; 40% less than the previous holiday quarter.

Throughout the past two quarters, the average number of attack vectors employed in DDoS attacks per IP per day has been mostly steady at approximately 1.4, with a maximum of 10.

Over the past quarter, we've seen over 34 different types of attack vectors on L3/4. ACK attacks formed the majority (50.1%) in Q1, followed by SYN attacks with 16.6%, and in third place, Mirai, which still represents a significant portion of the attacks (15.4%). Together, SYN & ACK DDoS attacks (TCP) form 66% of all L3/4 attack vectors in Q1.

Top Attack Vectors

All Attack Vectors

Attack Vector

Percent in Q1

ACK

50.121%

SYN

16.636%

Mirai

15.404%

UDP

5.714%

LDAP

2.898%

SSDP

2.833%

DNS

2.677%

Other

0.876%

QUIC

0.527%

NTP

0.373%

RST

0.353%

Memcached

0.296%

ChargeGen

0.236%

WS Discovery

0.221%

ACK-PSH

0.208%

SNMP

0.159%

VSE

0.081%

MSSQL

0.079%

ICMP

0.072%

Bittorrent

0.056%

OpenVPN

0.046%

Dahua

0.032%

GRE

0.022%

TFTP

0.014%

LOIC

0.014%

STUN

0.011%

Lantronix

0.009%

CoAP

0.008%

Jenkins

0.006%

VXWorks

0.005%

Ubiquity

0.005%

TeamSpeak

0.004%

XMAS

0.003%

SPSS

0.001%

A Crisis is Unfortunately Sometimes a Malevolent Opportunity

The number of DDoS attacks in March 2020 increased as compared to January and February. Attackers found the crisis period to be an opportune time to launch an increased number of DDoS attacks, as illustrated below.

Furthermore, as various government authorities started mandating lockdowns and shelter-in-place orders, attackers resorted to increasing the number of large-sized attacks in the latter half of March. There were 55% more attacks observed in the second half of month (March 16-31) as compared to the first half (March 1-15). Additionally, 94% of attacks peaking at 300-400 Gbps were launched in the month of March.

Stop DDoS attacks, Large or Small, Closer To The Source

With the ever shifting DDoS landscape, it is important to have a DDoS protection solution which is comprehensive and adaptive. In context with the attack insights illustrated above, here’s how Cloudflare stays ahead of these shifts to protect our customers.

As attacks shrink in rate and duration, Time To Mitigate SLAs as long as 15 minutes provided by legacy vendors are just not practical anymore. Cloudflare mitigates network layer DDoS attacks under 10 seconds in most cases, which is especially critical for the increasingly shorter attacks. Read more about the recent enhancements to our DDoS detection and mitigation systems that allow us to automatically detect and mitigate DDoS attacks so quickly at scale.

An increasing number of DDoS attacks are localized, which implies that legacy DDoS solutions which adopt a scrubbing center approach are not a feasible solution, as they are limited in their global coverage as well as act as a choke point, as DDoS traffic needs to be hauled back and forth from them. Cloudflare’s unique distributed architecture empowers every one of its data centers, spanning across 200 cities globally, to provide full DDoS mitigation capabilities.

Large distributed volumetric attacks still exist and are employed by resourceful attackers when the opportunity is rife. An attack exceeding 1 Tbps can be expected in the future, so the ability to mitigate large DDoS attacks is a key aspect of today’s DDoS solution. Cloudflare has one of the most interconnected networks in the world with a capacity of over 35 Tbps which allows it to mitigate even the largest DDoS attacks. This massive network capacity concomitant with the globally distributed architecture allows Cloudflare to mitigate attacks, both small and large, closer to the source.

Over the past 6 months, volumetric DDoS attacks decreased by 82%. However volumetric attacks are not gone yet, still peaking as high as 418 Gbps. In this post, we cover the changing attack landscape and how Cloudflare adapts and evolves to keep the internet safe....

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